Conductive wound dressings and methods of use

ABSTRACT

Wound treatment dressings comprising combinations of at least one conductive layer, at least one absorbent layer or a moisture regulation layer, and methods of making and methods of use are disclosed for treatment of wounds in humans and animals. The novel dressings aid in healing by helping restore the transepithelial potential of the skin, providing a functional anti-microbial barrier, and allowing for regulation of the moisture content of the wound without disturbing the wound.

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims benefit to U.S. Provisional ApplicationNo. 60/374,769 filed Apr. 23, 2002. This application is also acontinuation-in-part of U.S. patent application Ser. No. 09/531,245filed Mar. 21, 2000, which is a continuation of pending priorInternational Application Serial No. PCT/US98/19689 filed on Sep. 22,1998, which claims priority to U.S. patent application Ser. No.08/935,026 filed on Sep. 22, 1997, all of which are incorporated hereinby reference in their entirety.

TECHNICAL FIELD OF THE INVENTION

[0002] The present invention relates to compositions and methods for thetreatment of wounds. More particularly, it relates to moistureregulating wound dressings that maintain a moist wound healingenvironment, create a functional microbial barrier, reduce microbialbioburden of the wound, and aid in healing and pain reduction.

BACKGROUND OF THE INVENTION

[0003] The treatment of wounds has become a highly developed area ofscientific and commercial investigation because increased rates ofhealing reduces healthcare costs and decreases the risk of complicationsdue to secondary infections. It is currently believed that healing isrelated to the degree of injury, the immunological and nutritionalstatus of the host, contamination of the wound, the maintenance of themoisture level, pH and oxygen tension of the wound surface, and theelectrical parameters of the wound site in relation to the surroundingintact, uninjured tissue. In particular, regeneration in amphibians andfracture healing in mammals are associated with complex changes in thelocal direct current (DC) electric field. It is believed that theelectric field gradually returns to normal pre-injury levels as theinjury heals. Conversely, failure of the normal healing process, forexample as in fracture non-unions, is associated with the absence ofappropriate electrical signals at the site of the injury.

[0004] There have been numerous studies conducted on wound healing inamphibians because their rate of healing is significantly greater thanthat of mammals. Wound healing in mammalian skin occurs over days oreven weeks, with epithelial cell migration rates ranging from 7 (drywound) to 20 (wet wound) micrometers/hour. Amphibian skin wounds healwithin hours, with epithelial cell migration rates ranging from 60 tomore than 600 micrometers/hr. The expedited rates of healing inamphibian skin may be partially explained by the aqueous environmentthat bathes the outer surface of the epithelium., Amphibian wounds in anaqueous environment are provided with the appropriate ions tore-establish the electrical potential on the surface of the wound aswell as provided with an environment favorable to cell migration andreproduction.

[0005] It is generally recognized that dry wounds in mammals heal moreslowly than wounds that are kept moist by occlusive dressings. Keepingthe epidermis surrounding a wound and the wound itself moist stimulatesthe wound to close. Wound dressings have been designed to retainmoisture from the exudates produced by the wound and function bypreventing evaporation of fluid. Wounds that are dry and lack productionof exudate must depend upon the moisture within a self contained wounddressing. If the wound dressing dries out, the needed moisture level foroptimum wound healing will not be maintained and the dressing will stickto the wound surface and cause disruption of cellular processes. Thelack of moisture often results in the formation of an eschar or scab,and a general slowing of the wound healing process.

[0006] Wounds that produce an extensive amount of moisture are thoughtto create another problem called skin maceration. Skin maceration is asoftening of the skin or wearing away of the skin as a result ofcontinual exposure to bodily fluids or moisture. It is known to cause abreakdown of the cornified epithelium, thereby reducing the physicalmicrobial barrier function as well as the moisture regulation functionof the epidermis. With a reduction of the microbial barrier function,the wound surface has a significantly greater risk of contamination bypathogenic microbes from the surrounding environment. Therefore, it iscommon practice to design wound dressings to reduce or prevent skinmaceration by wicking away wound fluids and storing the fluids inabsorbent layers.

[0007] A common practice in the treatment of wounds is the applicationof impermeable backing sheets to a wound dressing. The backing sheetfunctions as a moisture retention layer as well as a physical barrier toprevent microbial penetration. The backing sheet typically consists of amaterial with specified moisture vapor transmission rates (MVTR) andprovides control of the rate of evaporation of moisture from theabsorbent layer. Therefore, the backing sheet is generally impervious toliquid.

[0008] There are a variety of venting systems that can be containedwithin the dressing structure for the purpose of directing woundexudates via specific pathways to provide a controlled leakage of fluidsfrom the wound surface to a contained absorbent layer. For example, incertain perforated films, the perforations are sufficient to permitwound exudates to diffuse through the film at a rate that precludespooling on the wound surface, which is a common cause of maceration.These dressings must be removed when they become saturated withexudates.

[0009] While there are numerous dressings designed to retain themoisture content of wounds, there are still many areas of inefficiencyin current treatment methods. For example, these dressings are onlyeffective for moist wounds and do not provide any significant benefitfor dry wounds. Wounds vary significantly in the amount of exudates ormoisture produced throughout the healing cycle. In order to maintain aneffective level of moisture it is necessary to continually change thedressings as the absorbent component reaches maximum capacity.Conversely, it is necessary to remove the dressings and add fluid to drywounds, then replace the dressings. In either situation, removal of thedressing can cause disruption of the cellular process of the wound andincrease the risk of contamination by microbes. Furthermore, it isnecessary to change the types of dressings throughout the healingprocess of the wound as the moisture content changes.

[0010] Besides the effect of moisture on wound healing, microbial growthat the site of injury has a great effect on healing. In normal skin, amicrobial barrier is created by the cornified epithelium. Wounds causedestruction of the cornified epithelium as well as deeper layersthereto, and the loss of the natural anti-microbial barrier.

[0011] The presence of microbial species at the wound site creates abioburden that can retard the healing process. As the bioburden of thewound decreases to bacterial counts less than 10³ CFU/ml, wound healingis enhanced. Treatment of wounds typically involves preventingcontamination by pathogenic microbes from the external environment aswell as reducing the microbial bioburden of the wound.

[0012] While there are scores of antibacterial and antifungal agentsthat can be used to treat wounds, the anti-microbial and antifungalproperties of silver have been of particular interest. However, theeffectiveness of silver as an anti microbial agent is at least partlydetermined by the delivery system. Most silver compounds that dissociatereadily and produce large numbers of free silver ions are highly toxicto mammalian tissues. Less-toxic compounds, including silversulfadiazine cream, widely used in the treatment of burns, do notdissociate readily and therefore do not release large numbers of silverions. Therefore, these compounds must be re-applied frequently tomaintain their clinical efficacy.

[0013] Silver has been used in the construction of wound dressings toactively or passively release metallic silver particles or silver ionsinto the wound. Active release of silver ions require the presence of anelectrical potential that actively drives silver ions from a source intothe wound dressing or wound itself. This has been accomplished with abattery or other power source known to those skilled in the art. Passiverelease of silver ions is dependent upon the solubility of silver inaqueous solutions. The passive release of silver ions has been calledthe oligodynamic release process and includes the passive dissolution ofsilver into a solution.

[0014] The anti-microbial efficiency of metallic silver or silver ionsis dependent upon the microbe coming into direct contact with thesurface of the metallic silver or coming into contact with a releasedsilver ion. Therefore, the total surface area of metallic silver and thenumber of silver ions released is directly related to the level ofanti-microbial activity. Various methods have been used to createmechanisms for metallic ion transfer.

[0015] For example, the vacuum vapor deposition technique has beenutilized in the construction of wound dressings to plate metallic silverand silver salts onto a variety of substrates. The vacuum vapordeposition technique has been modified so as to create “atomic disorder”of the plated silver that has been reported to enhance theanti-microbial effect by allowing the release of nanocrystalineparticles of metallic silver. However, the technique provides a flatplating pattern and does not uniformly coat the entire three-dimensionalsurface of fibers.

[0016] Another mechanism used for passive release of silver ions andparticles from a wound dressing includes imbedding or placing silverparticles of varying sizes in a variety of substrates. Finely dividedmetallic silver in collagen has been incorporated into surgicaldressings of reconstituted collagen foam laminated to a thick continuouslayer of inert polymer. This does not allow for direct contact of themaximum number of ions with the wound.

[0017] When connected to a voltage source, a metal anode and a returnelectrode have been used as a means to deliver silver ionsiontophoretically to a wound or within a wound dressing. Electricallyconductive silver-impregnated meshes, including silver-protein colloids,have been disclosed with current densities as low as 10 μA/mm². Thisrequires an external power source and stationary equipment and iscumbersome for the patient.

[0018] Silver foils have been incorporated into wound dressings as ameans of supplying silver ions as an anti-microbial agent, as well asacting as an electrode for dispensing medications. In addition, silverhas been fabricated into devices that incorporate a means of applying atherapeutic voltage to the wound. Foils do not provide for circulationof air, and are limited in surface area.

[0019] Compounds that slowly release silver into the wound environmenthave been disclosed in substances such as water soluble glass,phosphorus pentoxide and silver oxide. The silver impregnated glass maybe in the form of a powder, granules, or woven into a dressing. Thewater soluble glass releases silver secondary to the dissolution of theglass. Such compositions have a high volume resistance and very poorconductivity.

[0020] Regardless of whether silver is provided in the form of silverions or as a topical composition (silver nitrate solution, silversulfadiazine cream, or the like), its beneficial effects are manifestedprimarily at the treated surface and immediately adjacent tissues, andare limited by the achievable tissue concentration of silver ions.Despite the availability of numerous techniques for the delivery ofsilver and silver compounds in vitro and in vivo, there remains a needfor a delivery system that is capable of supplying clinically usefulconcentrations of silver ions to a treatment site without the need foradjuvant electrical stimulation.

[0021] None of the available metallic ion treatment devices provide anefficient and convenient means to restore the homeostaticelectromagnetic environment for areas of wounds. They also do notprovide for maximum surface area for release of metallic ions. Inaddition, the prior art does not address the need to regulate themoisture content of a wound without manually changing the dressings, orapplying liquids or medicants. This is true in part because of thebelief that a wound dressing must serve as a microbial barrier andprevent the movement of fluids from the wound exudates. The currentlyavailable treatments for wounds prevent microbial contamination byproviding a physical barrier which must be manipulated and interruptedas part of the treatment process. Such activities allow for microbecontamination and interrupt the healing process.

[0022] It is believed that wound healing occurs with maximum speed andefficiency when the wound is maintained in a moist condition withoutexcessive wetness or dryness. Wounds have variable hydration needs basedupon the type of wound and the phase of healing. There are many types ofwound dressings on the market to meet the differing needs of differenttypes of wounds, however, none provide for the regulation of the fluidcontent of the wound.

[0023] What is needed is a means for treating wounds that addresses theabove problems, and provides a functional anti-microbial barrier, allowsfor regulation of the moisture content of the wound, and aids inmaintaining the transepithelial potential across the epithelium.

SUMMARY OF THE INVENTION

[0024] The present invention relates to compositions and methods formaking moisture regulating wound dressings that can aid in restoring thetransepithelial skin potential, maintain a moist wound healingenvironment, create a functional microbial barrier, reduce microbialbio-burden of the wound, and aid in reducing pain.

[0025] The present invention comprises wound dressings and methods ofusing such dressings. Wound dressings of the present invention compriseone or more layers of materials. One of the layers can be a layercomprising metal-plated fibers, foams or combinations of fibers andfoams. This layer, referred to as the conductive layer, comprisesfibers, foams or a combination of fiber and foams that have fromapproximately 0% to approximately 100% of the surface or surfaces of thefiber or foam covered with a metal plating, and all ranges therebetween.

[0026] Fibers or foams that do not have metal plating are referred to asnonconductive and fibers or foams with metal plating are referred to asconductive.

[0027] Medical devices of the present invention can comprise a secondlayer that is an absorbant layer. Medical devices of the presentinvention can comprise a third layer that is a moisture control layer,which may be impermeable to gases or liquids or may have aperturestherein that allow transmission of differing materials such as gases,liquids or microbial or environmental contaminants.

[0028] Preferably, the at least one conductive layer can be placed incontact with a wound. At least a portion of the conductive layercomprises substrates coated with a coating of a metal. Fibers includebut are not limited to alginates, chitosans, polymers, synthetic andnaturally occurring fibers. Fibers may vary in composition and threedimensional structure. A preferred conductive layer comprises aplurality of fibers wherein at least one fiber comprises a threedimensional structure and the fiber is substantially coated with ametal. Another preferred conductive layer comprises a polymeric foamstructure wherein at least a portion of the foam surfaces aresubstantially coated with a metal, or the layer comprises a combinationof fibers and foams. The plurality of fibers or foams within theconductive layer comprise at least one fiber or foam, having itssurfaces coated with metal and include fibers or foams that are shapedto provide a spontaneous movement of fluids such as capillary action orwicking of fluids. Such fibers or foams are designed with grooves orchannels along the longitudinal axis of the fiber or foam and thesechannels serve as ducts to move fluids, store or trap substances andprovide a large surface area for a given denier per fiber or surfacearea of a foam.

[0029] Preferably, additional layers of the dressing include at leastone absorbent layer and at least one moisture regulation layer having aplurality of apertures disposed primarily in the moisture regulationlayer. The apertures may vary in size from a layer with no apertures toapertures in a size range that is occlusive to liquids but not to gases,to a size range that allows liquids and gases to pass through, to a sizethat is open to microbes, such as bacteria, viruses, fungi, parasites,and environmental contaminants.

[0030] An additional aspect of the invention relates to wound dressingsthat provide for a capacitive effect formed by the alternation ofconductive layers of fiber with non-conductive layers.

[0031] Another aspect of the invention relates to wound dressings havinga plurality of layers arranged according to the ratio of conductive tononconductive fibers comprising each layer. Additional aspects of theinvention relate to various configurations of the functional shape ofthe novel dressings. Another aspect of the invention relates to methodsof using the novel dressings to treat wounds in a human or an animal.Further aspects of the invention relate to methods of making the noveldressings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The invention is illustrated in the drawings in which likereference characters designate the same or similar parts throughout thefigures of which:

[0033]FIG. 1 is a schematic depiction of a cross-section of woundedmammalian skin with a dressing in accordance with an embodiment of thepresent invention positioned over the wounded area;

[0034]FIG. 2 is a graph of voltage verses position on the wounded skinas shown in FIG. 1;

[0035]FIG. 3A is a representative cross-section of polymericautocatalytic plated fibers on a non-conductive substrate;

[0036]FIG. 3B is a cross-section of one polymeric autocatalytic platedfilament from FIG. 3A;

[0037]FIG. 3C is a portion of the cross-section of one polymericautocatalytic plated filament of FIG. 3B;

[0038]FIG. 3D is an illustration of an enlargement of the metallicsurface of a polymeric autocatalytically plated filament representingapproximately 62 μm²;

[0039]FIG. 4 is a graphic representation of the ionic silver releaseconcentration from an autocatalytically silver plated fabric measured byinductively coupled plasma spectroscopy;

[0040]FIG. 5 is a graphic representation of the anti-microbial activityof an autocatalytically silver plated fabric;

[0041]FIG. 6A is an illustration of a possible geometric shape forapertures;

[0042]FIG. 6B is an illustration of a possible geometric shape forapertures;

[0043]FIG. 7 depicts a cross-section of FIG. 6 illustrating one aspectof a wound dressing;

[0044]FIG. 8 is an illustration of one aspect of an island wounddressing;

[0045]FIG. 9 is an illustration of a cross-section of FIG. 8;

[0046]FIG. 10 depicts of a cross-section of an alternative aspect of anabsorbent layer;

[0047]FIG. 11 represents a cross-section of an alternative aspect of awound dressing;

[0048]FIG. 12 is an illustration of a cross-section of an alternativeaspect of a wound dressing;

[0049]FIG. 13 illustrates of a cross-section of an alternative aspect ofan island wound dressing;

[0050]FIG. 14 is an illustration of a cross-section of a secondary wounddressing.

[0051]FIG. 15 is a cross-section of a two-layer autocatalyticly metalplated foam.

[0052]FIG. 16 is a cross-section of a one-layer autocatalyticly metalplated foam.

[0053]FIG. 17 is a cross-section of an autocatalytic metal platedfilament that provides spontaneous movement of fluids

DETAILED DISCLOSURE OF THE INVENTION

[0054] The present invention comprises compositions for medical devicesand methods for the treatment of wounds in a human or animal using thecompositions and medical devices. Though not wishing to be bound by anyparticular theory, it is believed that the wound dressings aid inhealing by (1) assisting with restoration of the transepithelial skinpotential; (2) creating an anti-microbial barrier to environmentalpathogens without restricting the passage of liquids and gases; (3)aiding in the regulation of the moisture content at the wound surfaceand of the dressing and allowing fluids to be manually added or removed,or to be added or removed by means of a secondary dressing; (4) allowingmedicants or liquids to be added to the wound dressing withoutdisturbing the wound surface; and (5) aiding in the reduction of painoriginating from the wound. The present invention comprises methods oftreating wounds and methods of making the novel dressings.

[0055] For purposes of the invention, the term “wound” refers to anywounds, internal or external to the body of a human or animal including,but not limited to, lesions, rashes, blisters, pustules, abrasions,hives, dermal eruptions, partial thickness wounds, partial thicknessburns, incisions, skin graft sites, skin donor sites, lacerations, StageI-IV dermal ulcers, venous stasis ulcerations, pressure ulcerations,arterial insufficiency ulcerations, diabetic ulcers, decubitus ulcers,organ lacerations, organ abrasions, organ tears, or external andinternal surgical wounds. For purposes of the invention, the term“organ” refers to any part of the body of a human or animal having aspecial function including, but not limited to, bone, muscle, skin,heart, eyes, liver, kidney, vascular system, lungs, reproductive organs,and the like. The term wound can also-refer to any abnormal condition ofan organ of a human or animal that results from mechanical orphysiological events or conditions.

[0056] As used herein, the terms “fiber” or “fibers”, “foam” or “foams”are interchangeable. Though the terms denote differently formedmaterials, where one of the terms is used, the other or the plural ofeither is intended.

[0057] Dressings are provided that control the moisture levels of thewound surface including controlling the moisture loss, altering theaperture or slit configuration of the dressing; altering the materialsof the wound contact layer; altering the absorbent characteristics ofone or more absorbent layers. Absorbent layer materials include, but arenot limited to, hydrogels, chitins, alginates, polyurethane foams,acrylates, hydrocolloids, collagens, and cellulosic materials.

[0058] The present invention comprises medical devices comprising layerscomprised of conductive material, absorbent material and moistureretention material wherein the layers can mean at least one layer, atleast two layers, at least three layers, at least four layers, at leastfive layers, at least six layers, at least seven layers at least eightlayers, at least nine layers, at least ten layers, and more.

[0059] In a first embodiment of the invention as illustrated in FIG. 7,the wound dressing comprises at least one conductive layer, at least oneabsorbent layer positioned adjacent the conductive layer or adjacent toa moisture regulation layer, and at least one moisture regulation layerpositioned adjacent to the absorbent layer or adjacent to the conductivelayer and comprising a plurality of apertures of varying sizes disposedsubstantially throughout and in the moisture regulation layer.

[0060] In devices of the present invention, at least a portion of theconductive layer comprises fibers or foams coated with a metal, whereinin a range of from approximately 0% to approximately 100% of thesurfaces of the fibers or foams are coated. The fibers or foams may haveareas of the length of the fiber or foam that are coated in a range offrom approximately 0% to approximately 100% of the surfaces. Forexample, in a 3 inch fiber, the first inch is uncoated, the surface orsurfaces of the second inch is 100% coated, and the third inch isuncoated.

[0061] Uncoated or non-conducting fibers and foams, including but notlimited to alginates, chitosans, polymers, synthetic and naturallyoccurring fibers or foams may be placed in the conductive layer. Themetal-plated fibers and foams and the nonconductive fibers and foamsvary in composition and may or may not have a functional threedimensional structure used for movement of fluid. A layer may include,but is not limited to a plurality of fibers wherein at least one fiberis coated with a metal, or a layer may include a polymeric foam whereinat least a portion of the foam comprises a three dimensional coating ofa metal, and preferably, a uniform coating of metal. The plurality offibers where in at least one fiber comprises a three dimensional coatingof a metal may also include fiber or foam shapes that provide movementof fluids, such as capillary action or wicking of fluids. The fibers orfoams are designed with grooves or channels along the longitudinal axisof the fiber or foams and serve as ducts to move fluids without apumping means, such as in capillary action, store or trap substances andprovide a large surface area or an active surface area for a givendenier per filament or foam. For purposes of the invention, the term“three dimensional coating” refers to the circumferential, concentric,uniform coating of all the surfaces of a fiber or foam which may be theentire length of the fiber or foam or may comprise one or more coatedsections of the fiber or foam. Preferably, during treatment, thedressing can be positioned with the conductive layer in contact with awound, or with the absorbent layer in contact with the wound.

[0062] The base substrate that is coated with a metal to form theconductive layer can be any biocompatible, flexible, synthetic ornatural material that can be formed into a film, fiber, foam, web, orany configuration capable of supporting a metal coating and combinationsof such forms. The base substrate materials can include, but is notlimited to carbon, polyamide, glass, KEVLAR®, acetate, flax, olefin,polyethylene, rubber, saran, spandex, vinyl, polyester, silk, wool,rayon, cotton, cellulose or combinations thereof. Configurations includefibers, films, foams or webs comprising blends, composite materials, ormulti-component fibers, either woven, knitted or non-woven. Someindividuals may have a topical hypersensitivity to certain fibermaterials, and the base fiber is preferably non-allergenic orhypoallergenic. It is to be understood that for purposes ofillustration, the discussion refers to fibers for the conductive aspectof the invention, but can also include conductive foams.

[0063] A preferred material for making fibers or foams used in thepresent invention is any materials that has a nitrogen group or asimilarly functional group capable of being sensitized, that isavailable for sensitizing the material for autocatalytic metal plating.If the material does not have a nitrogen group on the surface of thematerial, then a layer of different material, which provides a nitrogen,can be coated on the foam or fiber prior to sensitizing. For exampler,cross-linked polyethylene fibers are coated with polyamide to provide anitrogen group on the surface of the fibers. The polyamide-coated fiberis then sensitized for autocatalytic metal plating. Compositions andmethods for sensitizing materials for autocatalytic metal plating areknown to those skilled in the art and include, but is not limited to,tin chloride. After sensitizing the polyamide-coated fiber, a metal,such as silver, is autocatalytically plated onto the fiber. Theautocatalytic metal plating preferably provides a uniform metal coat tothe sensitized section of the fiber. The preceding description alsoapplies to metal plating of a foam.

[0064] Under optimum conditions, the conductive layer (114), whenmoistened, can be electrically conductive, non-adherent, liquid and gaspermeable, porous, and anti-microbial. The conductive layer may contactthe surface of the wound and the surface of normal tissue surroundingthe wound. Ideally, the composition of the conductive layer comprises aplurality of fibers, wherein at least one fiber is uniformly andconcentrically coated with a metal or metal alloy so that the coating isthree dimensional and covers all surfaces of the fiber. Ideally also,the conductive layer comprises a polymeric foam wherein the surface isuniformly and concentrically coated with a metal or metal alloy so thatthe coating is three dimensional and covers all surfaces of the foam Forpurposes of the invention, all or part of the fiber or foam can becoated three-dimensionally. Preferably, all or a plurality of thesurface area of the fibers or foam of the conductive layer (114) areauto-catalytically plated with metal to allow for a uniform, threedimensional coating of the metal or metal alloy and provide the maximumsurface area for release of metallic ions. The anti-microbial activityof released metallic ions and the metallic surface function as amicrobial barrier, and aid in preventing the migration of microbes fromthe surrounding environment to the wound surface, while at the same timeallowing fluids and gases to pass freely.

[0065] For purposes of the invention, any metal or metal alloy capableof being plated onto a substrate to form a conductive layer can be used.Metal elements suitable for the present invention include, but are notlimited to, platinum, copper, gold, nickel or silver, and/or binaryalloys of platinum, nickel, cobalt or palladium with phosphorus, orbinary alloys of platinum, nickel, cobalt or palladium with boron. Inone preferred aspect of the present invention the metal is silver. Forpurposes of explanation, silver is used to describe the invention,though it can be substituted with any other metal or metal alloy.

[0066] One embodiment of the present invention comprises devices havinga conductive layer that comprises areas of the layer having metals thatprovide a permanent or semi-permanent magnetic field. In a conductivelayer, if a current is generated by the movement of metal ions,particularly under moist conditions of fluid flow, an electric field anda transitory magnetic field are generated. By providing areas of thelayer with particular metals, such as isotopes of cobalt, asemi-permanent or permanent magnetic field can be provided to the woundsite. This magnetic field is not dependent on the fluid flow orgeneration of a current, but provides a steady magnetic field. Thoughnot wishing to be bound by any particular theory, it is believed that amagnetic field held in place at a wound aids in the healing processes.

[0067] Ideally, the metallic silver used for the invention is of highpurity, preferably from about 99.0% to about 99.6% pure, although lowerpurity levels can also function. It is believed that high purity reducesthe likelihood that contaminants or undesirable ions may contact orpenetrate the wound or skin.

[0068] Preferably, the substrate can be in the form of fibers. The rangeof denier of the fibers can be from about 0.0001 denier to about 10,000denier, preferably from about 1.0 denier to about 1000 denier, and morepreferably from about 5 denier to about 300 denier. The variouscross-sectional shapes that may be imparted to individual fibers areknown to those skilled in the art, and include, but are not limited to,round, oval, kidney-bean, dogbone, flat, tri-lobal, and multi lobal.Advantageously, a multi-lobal fiber such as the 4DG fiber commerciallyavailable from Fiber Innovation Technology Inc of Johnson City TN canincrease the surface area by 250% to 300% compared to round fibers.Fiber configurations that are capable of spontaneously transportingwater on their surfaces are also available and include a number offibers similar to the 4DG fiber. In general, while not wishing to bebound to any particular theory, it is believed that the greater thesurface area of the fiber, the greater the surface area of metallicplated fibers, forming an active surface area, which can result ingreater release of metallic ions and a more effective dressing.

[0069] Individual fibers may be fabricated into several different typesof yarns including, but not limited to, spun yarns, filament yarns,compound yarns, fancy yarns, and combinations thereof. Fibers can beconfigured into tow and floc and can be provided in the form of stapleor bulk continuous filament. The filament and compound yarns thatexhibit multiple longitudinal filaments are preferred. It is believedthat the greater the continuity of the yarns, the greater the potentialfor excellent conductivity when plated. Fibers and/or yarns can beassembled into fabrics, including but not limited to, woven fabrics,twisted and knotted fabrics, knit fabrics, non-woven fabrics, andcompound/complex fabrics. It is proposed that the total surface area ofthe fibers that compose the filaments, fibers, yarns or fabric is avariable in determining conductivity as well as passive metal ionrelease into aqueous fluids

[0070] It is preferable that the autocatalytically metal-plated surfaceshave a broad range of resistance from about 1,000 kiloohms/in² to about0.0001 ohms/in², a middle range from about 10 kiloohms/in² to about0.001 ohms/in² and an optimal range from about 10 ohms/in² to about 0.1ohms/in². It is believed that resistance decreases with increasingnumbers of plies or fibers within a layer. Preferably, beyond four pliesof conductive fabric, the resistance decrease may become non-appreciablefrom a clinical point of view, although the resistance may continue todecrease with additional layers. The preferable upper limit of thenumber of plies of conductive fabric can be about ten. Cost, thickness,composition, fiber density and weave structure and other factors mayalso be considered in selecting the number of plies. A more dense fabricdesign may need only one ply to achieve the same resistance measurementas a fabric having more than one ply of a highly absorbent material thatis less dense. The reduction of the resistance of the conductive layercan relate to the manner in which the fabric is plated and secondarilyto how the layer is constructed. It is believed that fabrics havingcontinuous fibers or fibers melted together can appear to have lowerresistance with greater continuity of the metallic layer. It is thoughtthat the larger the surface area of fiber contact, the better theconductivity and the lower the resistance. It is also believed that thepolymeric foam materials that are autocatalyticly metal plated provide alarge surface area of metallic silver with low resistance and highconductivity.

[0071] A preferred aspect of the conductive layer is a non-conductivepolymeric filament/fiber substrate that has been autocatalyticallyplated with silver. FIG. 3A is a representative cross-section of apolymeric autocatalytically plated fabric composed of multifilamentsformed into yarns and knitted into a fabric. FIG. 17 represents amutilobular fiber that is uniformily metal plated on all surfaces. Allfilaments, (40) are three dimensionally coated with a uniform layer ofmetal (41). FIG. 3B represents a cross-section enlarged detail of FIG.3A showing the uniform metallic coating (41) of one filament (40). FIG.3C is an enlarged detail of FIG. 3B showing the uniformity of metallicplating covering the polymeric substrate. FIG. 3D is an enlargement ofthe metallic surface of a polymeric autocatalytically plated filamentrepresenting approximately 62 μm² of surface area.

[0072] Another preferred aspect of the conductive layer is anon-conductive polymeric foam substrate that has been autocatalyticallyplated with silver. FIG. 15 and FIG. 16 are representativecross-sections of a polymeric autocatalytically plated foam. FIG. 15represents a polymeric foam substrate (151) with a second polymeric foamcoating (152) that is in turn autocatalytically metal plated (153). FIG.16 represents a polymeric foam substrate (160) that is autocatalyticallymetal plated (161). Open spaces are represented in FIG. 15 and FIG. 16by 162 and 154. All metal plated surfaces are three dimensionally coatedwith a substnatially uniform layer of metal.

[0073]FIGS. 3A, 3B, 3C and 3D demonstrate that the actual surface areaof metallic silver exposed to a liquid can be significantly greater thanthe geometric surface area of the fabric. Assuming the surface of theplated metal is smooth, the ratio of geometric surface area to actualsurface area can have a range from about 1:2 to about 1:10,000, fromabout 1:10 to about 1:1000, from about 1:10 to about 1:500, 1:20 toabout 1:500, from about 1:20 to about 1:250, from about 1:10 to about1:250, from about 1:10 to about 100 and an optimal ratio range fromabout 1:20 to about 1:100. Taking into consideration FIG. 3D, it isbelieved that the actual surface area can be extended by a multiple ofbetween about 10 and about 1000 above the calculated smooth surfacearea. Even though a uniform coating is preferred, there may beapplications wherein non-uniform coatings are preferable.

[0074] The thickness of the uniform coating can vary from about 0.1micrometers to about 2.0 microns, from about 0.1 microns to about 1micron, from about 0.1 microns to about 1.5 microns, preferably fromabout 0.2 microns to about 1.5 microns. Preferably, the thickness ofmetal coating is directly correlated with the percentage of weight ofsilver plated to the weight of the fabric without silver plating. Theamount of coating can vary from about 5% to about 40% by weight, fromabout 5% to about 30% by weight, from about 5% to about 20% by weight,from about 5% to about 10% by weight, from about 10% to about 30% byweight, from about 10% to about 25% by weight, from about 10% to about20% by weight, from about 15% to about 30% by weight, more preferablybetween about 15% to about 22% by weight. While not wishing to be boundto any particular theory, it is believed that filaments and fibers thatare uniformly plated may have the greatest electrical conductance andthe lowest electrical resistance. Preferably, the maximum conductanceand minimum resistance can be directly correlated. Preferable for theinvention is a plating thickness between about 0.2 to about 1.5 microns,and between about 14% to about 22% of the weight of the plated fabriccomposed of metallic silver. Most preferably, the conductivity of theplated fiber can significantly decrease when the percent of weight ofplated fabric falls below about 10%. Silver-coated fibers suitable foruse in the present invention are commercially available from ConductiveSpecialty Fabrics Manufacturing, Lakemont, Ga.

[0075] The dressings can also comprise at least one absorbent layer(116) that functions primarily as a reservoir for receiving and storingwound exudates or other fluids. The absorbent layer may provide a sourceof moisture in wounds with minimal fluid drainage or exudate byreceiving and holding fluids that are provided from an external sourcethrough a plurality of apertures in layers superficial to the absorbentlayer. The absorbent layer may contain any number of layers ofconductive metal plated fibers uniformly mixed with non-conductivefibers. The absorbent layer can also comprise only non-conductive fibersor material. For purposes of the invention, non-conductive fibers ormaterial are any fibers or materials that are not coated with a metal ormetal alloy and are not capable of conducting an electrical charge orreleasing ions.

[0076] The at least one absorbent layer can comprise any absorbentmaterial, and the dressing can comprise any number of absorbent layerspositioned adjacent to any other layer of the dressing. Advantageously,the absorbent layer can be positioned adjacent to the moistureregulation layer. In another aspect of the invention, the absorbentlayer can be positioned between the conductive layer and the moistureregulation layer.

[0077] Absorbent materials suitable for the absorbent layer comprise anybiocompatible synthetic or natural absorbent material known in the artincluding, but not limited to, a foam, a sponge or sponge-like material,cellulosic materials, cotton, rayon, polyvinyl alcohol, polyvinylacetate, polyethylene oxide, polyvinyl pyrrolidon, polyurethanehydrocolloids, alginates, hydrogels, hydrocolloids, hydrofibrils,collagens or any combinations thereof.

[0078] In one aspect of the absorbent layer, layers of metal platedconductive fibers and non-conductive fibers can be uniformly distributedthroughout at least one, and preferably more layers. Alternatively,metal or metal alloy plated and non-conductive fibers can be uniformlydistributed throughout the absorbent layer. It is contemplated as beingwithin the scope of the present invention to have layers of absorbentmaterial of differing ratios of metal plated conductive fibers tonon-conductive fibers as well as differing thicknesses of the layers.The layers may be in the form of woven, knitted or non-woven fabrics.The absorbent layer (130) demonstrated in FIG. 10 is composed of layers(131, 132, and 133) of the absorbent material with varying ratios ofmetal plated conductive fibers to non-conductive fibers and varyinglayer thicknesses. As the concentration of metal plated conductivefibers increases and the concentration of non-conductive fibersdecreases, the ratio of metal plated conductive fibers to non-conductivefiber increases. As the concentration of metal plated conductive fibersdecreases and the concentration of non-conductive fibers increases, theratio of metal plated conductive fibers to non-conductive fibersdecreases. In a given layer, the ratio of metal or metal alloy platedconductive fibers to non-conductive fibers can be from about 1:100 toabout 1:0, from about 1:75 to about 1:0, from about 1:60 to about 1:0,preferably from about 1:50 to about 1:0, from about 1:40 to about 1:0.from about 1:30 to about 1:0 and more preferably from about 1:25 toabout 1:0. In the situation wherein the layers comprise about 100%conductive metal fibers, the ratio would be about 1:0. The ratio ofconductive metal or metal alloy plated fibers to non-conductive fibers,although constant within a given layer, may vary from layer to layer.Advantageously, there can be an increasing ratio of conductive metalplated fibers to non-conductive fibers the closer the layer is to thewound. Thus, there can be a decreasing concentration gradient ofconductive metal fibers in each subsequent layer further from the woundsite. Concentration gradients of mixed fibers can be made according toprocesses known to those of ordinary skill in the art.

[0079] The thickness of layers (131, 132 and 133) of FIG. 10 may besimilar or may vary. Ideally, the thickness of the layers increases asthe distance from the wound surface increases. In an additionalpreferred aspect, the increasing thickness of the layers occurs in aratio of the fibonacci numbers (i.e. 1,2,3,5,8,13,21 . . . ).

[0080] In another aspect of the absorbent layer, shown in FIG. 12, amultilayer structure (140) comprises conductive layers (141, 142, 143),with a non-conductive layer (144) interposed between conductive layers(141) and (142), and a non-conductive layer (145) interposed betweenconductive layers (142) and (143). The composition of conductive layersmay be similar and formed from conductive metal plated fibers or amixture of conductive metal or metal alloy plated fibers andnon-conductive fibers in the form of a woven, knitted or non-wovenfabric. The mixture of conductive metal or metal alloy plated fibers andnon-conductive fibers can be uniform in each layer and may have adecreasing ratio of conductive plated metal fibers to non-conductivefibers the closer the layer is to the wound surface. A layer ofnon-conducting, flexible material can be positioned between theconductive layers. In one aspect, the non-conductive layers can becomposed of impermeable or semi-permeable materials with aperturesdisposed substantially throughout. In FIG. 12, the use of thealternating conductive metal plated fiber layers (141, 142 and 143) andnon-conductive fiber layers (144 and 145) can create a capacitor-likelaminate.

[0081] The moisture regulation layer (118) shown in FIG. 7, can be anybiocompatible semi-permeable or impermeable material for limiting theevaporation of moisture from the absorbent layer and the wound surface.At least one moisture regulation layer (118) can be positioned adjacentto the conductive layer or adjacent to the absorbent layer of thedressing. Advantageously, the moisture regulation layer can bepositioned adjacent to the absorbent layer and can be fixedly attachedor removably attached for easy removal and replacement.

[0082] The moisture regulation layer not only controls the rate ofmoisture evaporation from the absorbent layer, but also functions as aphysical barrier to the penetration of microbes from the surroundingenvironment. The rate of moisture evaporation from the moistureregulation layer is related to the size of the apertures. Very smallaperture sizes allow the release of gases but not liquids, while largeraperture sizes allow the release of gases and liquids. Even larger-sizedapertures allow the entry of microbes such as bacteria and fungi andenvironmental contaminants. Though not wanting to be bound by anyparticular theory, it is theorized that the placement of apertureslarger than the size of microbes (such as bacteria and fungi) in thislayer runs counter to the prevailing teaching that a physical barriermust be provided to prevent the penetration of microbes from thesurrounding environment. The present invention substitutes thetraditional physical anti-microbial barrier to microbial penetrationwith a functional anti-microbial barrier through application of theanti-microbial metal plated fibers. The functional anti-microbialbarrier of anti-microbial metal plated fibers has allowed the aperturesto be placed in the moisture regulation layer without fear of compromiseof the physical barrier to environmental microbial contamination of thewound.

[0083] The moisture regulation layer can be a film, fabric or foam. Somepreferred materials include, but are not limited to, polyurathanes,polyolefins such as linear low density polyethylene, low densitypolyethylene, ethylene vinyl acetate, vinylidene, chloride copolymer ofvinyl chloride, methyl acrylate or methyl methacrylate copolymers andcombinations thereof. A preferred polymeric material is polyurethane,either as a film or as a polyurethane foam. The polyurethane may be anester or ether based polyurethane. Materials suitable for a foammoisture regulation layer can be any semi-permeable or impermeablenatural or synthetic compound including, but not limited to, rubber,silicon, polyurethane, polyethylene polyvinyl, polyolefin, orcombinations thereof.

[0084] Alternatively, the moisture regulation layer, (118), may be atransparent elastomer film for visual inspection of the moisture statusof the absorbent layer dressing. Preferably, the film can have athickness from about 10 μm to about 100 μm, from about 10 μm to about 90μm, from about 10 μm to about 80 μm, from about 15 μm to about 100 μm,from about 15 μm to about 90 μm, from about 15 μm to about 80 μm, fromabout 151 μm to about 70 μm, from about 20 μm to about 100 μm, fromabout 20 μm to about 90 μm, and more preferably from about 20 μm toabout 80 μm. In some materials, a thickness below 10 μm may result inpoor mechanical strength or handling properties and a thickness of thetransparent elastomer film exceeding about 100 μm may result in poorflexibility and comfort to the body. Preferably, the moisture regulationlayer has an MVTR of from about 300 to about 5,000 grams/meter/24 hours,preferably from about 800 to about 2,000 grams/meter/24 hours. Themoisture regulation layer can be laminated to the absorbent layer bymethods well recognized in the art.

[0085] To regulate the moisture level of the wound dressing, apertures,(111) as illustrated in FIGS. 6A and 6B, are disposed in the moistureregulation layer. The apertures can be any geometric shape having curvedlines, straight lines, or a combination thereof. Shapes include, but arenot limited to, slits, stars, oval, circles, semicircles, squares,rectangles, polygons or any combination thereof. The apertures can bedisposed randomly or in uniform patterns, groups, or bunches. Suchapertures allow for addition or removal of liquids from the absorbentlayer. In a method of use for wound treatment, the apertures would allowthe wound to be bathed by dispensing liquids, medicaments, cleansing ortreating agents, without removing the dressing.

[0086] The size of the apertures can improve the regulation of themoisture level of the absorbent layer, the conductive layer, and thesurface of the wound. It is believed that the regulation of the moisturelevel in the wound provides benefits such as the release ofanti-microbial metallic ions from the conductive metal plated fibers andfabrics and enhances the analgesic effect, improves conductivity of theconductive metal plated fibers, and assists with restoration of theelectrical potential of the wound site. As a result, while not wising tobe bound to any particular theory, it is believed that the cellulargrowth and regeneration is enhanced, expediting the healing of thewound.

[0087] Large apertures in general can cut through one layer or multiplelayers. The apertures are positioned to allow direct liquid andmedicants to be administered from the external environment to theabsorbent layer. The apertures (111) of the multilaminate wound layerdressing (110) of FIGS. 7 and 14 are cut through the moisture regulationlayer and are not cut through the absorbent layer or other layersbetween the moisture regulation layer and the surface of the wound. Theapertures (111) of the multilaminate island wound dressings, (120) ofFIG. 9 and FIG. 13 (150), are cut through the backing sheet, theadhesive layer, and the moisture regulation layer. With respect to theisland wound dressing, (120) of FIG. 9, the aperture pattern is limitedto the area over the moisture regulation layer. The apertures in theisland dressing of FIG. 9 extend through a back sheet layer (112),adhesive layer (119) and moisture regulation layer (118).

[0088] Advantageously, a semipermeable or impermeable moistureregulation layer can be laminated to an absorbent layer such that,regardless of the pattern of apertures, delamination of the moistureregulation layer from the absorbent layer does not occur. The aperturesallow for movement of fluids or medicants to and from the absorbentlayer. The regulation of moisture content can be controlled byapplication of fluids via a bulb syringe or similar application device,or alternatively by a secondary dressing (120) as shown in FIG. 14.

[0089] In alternative aspects of the invention, it is helpful to providea moisture regulation layer that is releasably or removably attached toan absorbent layer or a conductive layer of the dressing. This allowsfor the removal and replacement of the moisture regulation layer withoutdisturbing the wound. The moisture regulation layer can be affixed tothe adjacent layer by any artful means that will allow for quick removalfrom the absorbent layer including, but not limited to, adhesives,knitting techniques, lamination, or a combination thereof.

[0090] The layers of the devices of the present invention may or may notbe attached to each other or be provided as a component of anotherstructure. For example, a metallic, conductive layer, made frommetal-plated fibers, is applied directly to the affected site, such as awound. A foam is then applied as a second layer above the site toprovide the absorbant layer. A moisture retention layer is then placedon the surface of the foam farthest from the affected site to controlthe moisture content of the affected site. In another example, a two orthree layer bandage, comprising at least a conductive layer as the firstor second layer closest to the affected site, is provided wherein thelayers are attached to one another.

[0091] In any aspect of the present invention, the conductive layer canbe positioned in the dressing for placing in direct contact with thewound surface upon application of the dressing to the wound.Alternatively, the absorbent layer can be positioned in the dressing forplacing in direct contact with the wound surface upon application of thedressing to the wound. For treatment of internal wounds, for example fortreating surgical wounds on internal organs, the conductive layer orabsorbent layer can also be positioned for placement in direct contactwith the wound surface upon application of the dressing to the wound.

[0092] The various aspects of the wound dressings of the presentinvention can comprise an optional adhesive layer positioned between anyadjacent layers, or advantageously, the adhesive layer can be the toplayer of the dressing. Useful adhesives include those known in the wounddressing art, including but not limited to, rubber-based, acrylic, vinylether and hydrocolloid pressure sensitive adhesives. Conveniently,anti-microbial agents can be added to the adhesive material.

[0093] The wound dressings of the present invention can be formed intoany of a number of possible shapes, patterns or geometries, dependingupon the application and topography of the wound or application site.Any aspect of the wound dressing of the present invention can bemanufactured in a variety of shapes and configurations. For example,configurations can include, but are not limited to, compressive wraps,tampons, tubular, roll gauze, pads of varying sizes and shapes, islanddressings, strip dressings, dressings for dental applications, rectaldressings, vaginal pads, surgical packing or dressings, or anycombination thereof.

[0094]FIG. 11 shows a tubular configuration of the wound dressing. Thetubular configuration may be composed of one or more layers. The layerscan be composed of about 100% metal plated fibers or foam or a ratio ofconductive metal fibers or foam to non-conductive fibers or foam. Thetubular configuration can take the shape of a wrap for circumferentiallyplacing around an area to be treated. The distribution of conductivemetal fibers and non-conductive fibers in each layer can be uniform. Theconductive metal plated fibers of layers 131 a, 132 b and 133 crepresent an increasing ratio of conductive metal plated fibers tonon-conductive fibers as the layers are positioned closer to the woundcontact surface. The layers can be in the form of a woven, knitted ornonwoven fabric. The tubular configuration of this aspect of theinvention can be used in dressing applications including, but notlimited to, a vaginal, mouth, nasal, external ear canal, or rectal areadressing.

[0095] Another wound dressing configuration is the island dressing.FIGS. 8, 9 and 13 demonstrate various representative aspects of islanddressings. FIG. 8 shows the top view of a dressing with placement of theapertures (111) over the conducting layer (114), the absorbent layer(116), and the moisture regulation layer (118) but not in the peripheralarea of an adhesive layer. The cross-section line 8-8 of FIG. 8 is shownin FIG. 9. A release liner layer (117) extends the entire surface of anadhesive layer (119) on the moisture regulation layer (118). The releaseliner layer is removed prior to application of the island dressing to awound surface. An adhesive layer (119) is laminated to a backing sheet(112), and may include pressure sensitive adhesives for securing thedressing over the wound.

[0096]FIG. 13 illustrates an example of a multi-layer wound dressing inan island configuration, (150) having the same laminar composition asthe dressing (120) shown in FIG. 9, with the exception that conductivelayer (125) has been added between the absorbent layer (126), and themoisture regulation layer (128). The conductive layer (125) has similarcomposition to conductive layer (124). Both can be composed of about100% conductive metal plated fibers, woven, knitted or non woven. Themoisture regulation layer (128) can be adjacent to a backing sheet(122), that can be coated with a pressure sensitive adhesive (129) onthe surface that is facing the moisture regulation layer (128). Themoisture regulation layer, both conductive layers, and the absorbentlayer all have the same length and width, and are substantially ofsmaller dimensions than the backing sheet (122) and pressure sensitiveadhesive layer (129). They are also centrally seated on the adhesivesurface (129) and the backing sheet (122), leaving an edge of theadhesive layer exposed around the perimeter of the layers, thusproviding an island dressing configuration adapted for securing thedressing to the skin. Apertures penetrate through the backing sheet(122), the adhesive layer (129), and the moisture regulation layer (128)over the area covered by the moisture regulation layer, both conductivelayers and the absorbent layer, but not the perimeter area. A releaseliner layer (127) covers the entire perimeter of the adhesive layer(129) prior to use, in order to prevent premature, unwanted contact ofthe adhesive-bearing surface.

[0097] In another aspect of the invention, a secondary dressing (160),illustrated in FIG. 14, may be applied to any aspect of the wounddressings (110, 120, 130, and 150) of the present invention. Thesecondary dressing provides a source for liquids and medicants that canbe added to the wound dressings in addition to, or in combination with,the manual application of fluids or medicants using devices such as abulb syringe. The secondary dressing (160) is composed of a pressureadhesive layer (142), an absorbent layer (141) and a semipermeablebacking layer (143). The dimensions of the secondary dressing correspondto the dimensions of the wound dressing.

[0098] The pressure sensitive adhesive layer (142) is continuous aroundthe perimeter of the secondary dressing. The pressure sensitive adhesivelayer secures the secondary dressing to the primary dressing over thearea of the apertures. The secondary dressing can be easily changed andremoved on an as needed basis without disturbing the healing of thewound. The adhesive may be any of the medical grade adhesives heretoforeemployed for application to the skin. The absorbent layer (141) maycontain a mixture of conductive metal plated fibers and non-conductivefibers, all conductive metal fibers, or all non-conductive fibers. Themoisture regulation layer (143) can be an impermeable synthetic film

[0099] The secondary dressing may be releasably secured to the primarydressing, such that the secondary dressing may be removed and replacedwithout removing or disturbing the primary wound contact dressing, forexample, when the secondary dressing becomes saturated with woundexudates. The secondary dressing can be designed for the removal ofexcessive wound exudates or for the addition of liquids and medicants.

[0100] In another aspect of the invention, a fabric comprising any ofthe various aspects having conductive layer, absorbtion layer andmoisture regulation layer of the present invention, can be provided.After assembly of the layers, the layers are laminated into a fabricsuitable for cutting and forming into various configurations of wounddressings or wound healing devices.

[0101] The present invention comprises wound dressings or devices,comprising, at least one conductive layer. The wound dressing canfurther comprise at least one absorbent layer or at least one moistureregulation layer comprising a plurality of apertures disposed in themoisture regulation layer or any combination of the layers. Apertures ofthe moisture regulation layer allow passage of materials ranging in sizefrom no passage of materials, that is moisture regulation layers with noapertures, apertures that allow gases but not liquids to pass, toapertures that allow liquids and gases to pass, to apertures of a sizesufficient for the passage of microbial or environmental contaminants.The dressings may comprise moisture regulation layers attached to atleast one absorbent layer or at least one conductive layer. Theconductive layer may comprise at least one fiber that is coated threedimensionally with a metal or a metal alloy. The metal is selected fromcopper, silver, gold, palladium, nickel, cobalt or a combination thereofor the metal is selected from an alloy of nickel and boron, cobalt andboron, palladium and boron, nickel and phosphorus, cobalt andphosphorus, palladium and phosphorus, or a combination thereof. Theconductive layer may also comprise a polymeric foam coated threedimensionally with metal or a metal alloy. The conductive layer maycomprise at least one fiber or foam having grooves or channels along thelongitudinal axis of the fiber or foam for capillary movement of water,to store or trap substances, and to provide large active surface areasfor a given denier per fiber or foam.

[0102] Embodiments of the wound dressings of the present invention atleast one conductive layer comprising at least one conductive fibercomprising a three dimensional coating of a metal, and at least onenon-conductive fiber, wherein the conductive fiber and nonconductivefiber are uniformly distributed throughout the layer. The nonconductivefibers of the present invention can be composed of natural polymers,synthetic polymers, alginates, chitosan, rayon, cotton, or otherpolymeric substrates. Polyurethane is a preferable material forconductive and nonconductive fibers and foams. Absorbent layers cancomprise a plurality of layers wherein the ratio of conductive fibers tonon-conductive fibers is constant in a given layer or varies from layerto layer. In an embodiment, the ratio-of conductive fibers tonon-conductive fibers increases as the absorbent layer is positioned incloser proximity to the wound. Alternatively, the absorbent layercomprises conductive fibers comprising a three dimensional coating of ametal, and non-conductive fibers, wherein the conductive fibers andnonconductive fibers are uniformly distributed throughout the layer. Thesame arrangement of fibers and foams can be found in embodiments ofconductive layers. In the layers, the ratio of conductive fiber tonon-conductive fiber is between about 1:100 to 1:0, or the ratio ofconductive fiber to non-conductive fiber is between about 1:50 to 1:0,or the ratio of conductive fiber to non-conductive fiber is betweenabout 1:25 to 1:0.

[0103] Embodiments of the present invention may comprise a magneticfield provided to the wound surface by the conductive layer. A dressingmay further comprise an adhesive layer. The conductive layer maycomprises a fiber or foam three dimensionally coated with a metal. Theat least one moisture regulation layer may be positioned adjacent to atleast one absorbent layer. The layers may be shaped as polymeric sheets,films, or foams. An embodiment of a dressing may have multiple layers ofconductive and absorbent layers. The at least one absorbent layer maycomprise a plurality of layers, each layer increasing in thickness asthe proximity from the wound increases. Embodiments include dressingswhere the conductive layers and absorbent layers alternate. Thedressings may be formed into a shape selected from a pad, a tampon, atubular configuration, an island dressing, a strip dressing, or anycombination thereof. The apertures of the dressings may a geometricshape having curved lines, straight lines, or a combination thereof.

[0104] In treatment of wounds and use of the dressings described herein,a secondary dressing may also be used. A secondary dressing for applyingto a wound dressing comprising at least one absorbent layer, at leastone semi-permeable backing layer and a pressure adhesive layercontinuous around the perimeter of the backing layer. These and othersimilar embodiments are intended by the present invention.

[0105] The wound dressings of the present invention are advantageousover the prior art because they do not require an external energy sourceor galvanic cell action to create and deliver silver ions. The dressingsof the present invention can be formed into a number of different usefulforms, depending on the particular application. In addition, the propermoisture environment at the treatment site can be created and regulatedby controlling the amount of fluid at the wound site without disturbingthe wound.

[0106] Methods of Use

[0107] Healthy human skin exhibits an electrical potential across theepithelium that is referred to as the transepithelial potential (TEP) orepidermal battery. The TEP is generated by an active ionic transfersystem of sodium ions that enter the outer cells of the epithelium viaspecific channels in the outer membrane of these cells and migrate alonga steep electrochemical gradient. The epidermal battery is generatedthrough a series of electrogenic pumps that actively pump sodium ions,and tight gap junctions between epithelial cells that do not allow thereverse passage of the sodium ions. This results in the transport ofsodium ions from the water bathing the epithelium cells to the internalbody fluids of the animal, and causes the generation of a potential onthe order of 10 mV to 70 mV across the epithelium.

[0108] It is believed that when a wound is made in the skin, an electricleak is produced that short-circuits the TEP allowing the voltage toreverse at the wound surface. With the disruption of the epithelium'selectrogenic sodium transport mechanism within the wound, the TEP on thesurface of the wound is significantly altered in the reverse direction.As one progresses laterally from the wound surface to normal tissuesurrounding the wound, the potential across the skin increases, until apoint is reached at which the potential across the skin is the fullvalue normally found in unwounded skin. Thus a lateral voltage gradientis generated in the proximity of the wound margin as one transitionsfrom wounded tissue to normal tissue. Various studies have reported thatthe lateral voltage gradient in experimental animals could be as high as140 mV/mm. It has also been reported that within 24 hours after a woundis formed, the epidermally generated lateral voltage drops by 95%.Therefore, it is recognized that there is a lateral voltage gradient or“lateral potential” in the epidermis close to the margin of a wound. Thegreatest epidermally generated lateral voltage is found in the region ofhighest tissue resistance. In the amphibian, the locus of the majorlateral potential is at the high resistance space between the epidermisand the dermis. In the mammal, the locus of the major lateral potentialis at the space between the living and the dead cornified layers ofepithelium.

[0109] While not wishing to be bound to any particular theory, the roleof TEP in wound healing is explained in reference to FIG. 1 whichdemonstrates a cross-sectional representation of typical mammalian skin(5) with an electrical circuit generated by the TEP overlayed on theskin anatomy. The epidermis (7) overlies the dermis (9) at junction (11)and includes the stratum corneum layer (13) and the stratum spinosumlayer (15) with a junction (17) there between. The stratum corneum layeris composed of dead cornified squamous epithelium. The wound (19) isfilled with both cellular and dissolved elements of the blood includingfibrinogen, fibronectin, polymorphonuclear leukocytes, platelets and redblood cells. Depending upon the location on the body (24) the surface(21) of the skin distal to the wound (19) can be expected to have apotential in a range of from about −10 to about −70 milivolts due to theTEP. The resistance of the return paths of current that is induced by aphenomenon known as an epidermal battery (29) is represented byresistors (25). The resistance of the wound is represented at (27). Adressing (120) in accordance with the present invention and having ahighly conductive layer (114), absorbent layer (116), semipermeablelayer (118), adhesive layer (119) and backing sheet layer (112), isshown proximate to the wounded skin surface (21). Prior to placement ofthe dressing on the wound, the wound potential (23) is more positivethan on the surface of the skin (21), utilizing the surface potential tobecome less negative and, in certain instances, become positive. Whilenot wishing to be bound to any particular theory, it is believed thatthis is be due to the removal of the epidermal battery (29) at the wound(19). The further the potential test point (23) is from the unwoundedsurface (21), the more closely the potential will approximate thepotential of the positive side of the battery (29). If the wound is wetand therefore conductive, a wound current between points (31) and (33)will be induced by the TEP. The wound current will pass through theexudates and debris filling the wound (19) along the most efficient orlowest resistance path available. This is most likely proximate to theedge of the wound, because this will be the shortest path and the mostmoist path available. The wound current will pass from point (31)through the resistance at the junction (11) represented by resistor(35), into the wound at point (37), through the wound resistance (27) topoint (39), where it re-enters the epidermis (7) at the junction (17),through the resistance of junction (17), represented as resistor (25),to point (33) on the other side of epidermal battery (29).

[0110] While not wishing to be bound by any particular theory, it isbelieved that when the dressing (120) is placed on the wound (19), theconductive layer (114) lowers the electrical potential of the wound,(e.g., at 23) by virtue of electrical contact with uninjured skinsurfaces (21) which have a negative potential established by theepidermal battery (29). The dressing (120) lowers the potential of thewound surface and provides a conductive bridge between healthy skinsurfaces (21) on either side of the wound (19). The point of maximumresistance shifts from point (39) to point (37). This in turn shifts thepoint of maximum lateral potential drop from point (39) to point (37).With the shift in lateral potential, the electrical characteristics ofthe wound more closely resemble the amphibian wound than the mammalianwound. Amphibian wounds are known to heal significantly faster thanmammalian wounds because of this shift. Wound healing is enhanced andaccelerated by the shift caused by the highly conductive surface of thewound dressing of the present invention. The shift in lateral potentialfrom point (39) to point (37) can reduce the amount of stimulation thatsuperficial nerve endings receive, thereby aiding in creating ananalgesic effect. It is believed that the moisture level of the dressing(120) augments the restoration of the negative TEP and assists with theshift in lateral potential to deeper structures.

[0111]FIG. 2 is a representative graph of the voltage at the surface ofhuman skin as one proceeds from normal skin (21) to the open wound (23)to normal skin again. The area of normal skin (21) measures a relativelyconstant negative voltage between about 10 and about 70 milivolts. It isbelieved that the area of the wound surface where the TEP and theepidermal battery are disrupted (23) is always more positive thanuninjured skin (21), reaching voltages between (23′) and (23). When adressing (110) in accordance with the present invention is applied andthe wound is kept moist, it is possible to return to more normal skinpotentials as shown at (21′).

[0112] It is believed that the dressings of the present invention cancontribute to expedited healing of the wound and aid in providing relieffrom the pain associated with wounds. Without wishing to be bound by anyparticular theory, the principle mechanisms of action that may accountfor the pain relieving aspects of the dressing of the present inventioncan be derived from the conductive layers of the dressing. First, thesilver can create an antibacterial environment, which in turn candiminish the inflammation caused by the bacteria and subsequently candiminish pain. And second, the effect of a highly conductive layer canhave a positive effect on the electrical field environment of the woundto be healed.

[0113] The present invention comprises methods of treating a wound in ahuman or an animal comprising, a) applying a dressing to a wound on ahuman or animal wherein the dressing comprises at least one conductivelayer; at least one absorbent layer; and at least one moistureregulation layer comprising a plurality of apertures disposed in themoisture regulation layer; b) monitoring the absorbent layer of thedressing to determine a variation from a predetermined fluid level; andc) adding or removing fluid through the moisture regulation layer tomaintain the predetermined fluid level. Methods can further compriseaffixing a secondary dressing to the external surface of the dressingapplied in step a) to the wound, wherein the secondary dressingcomprises at least one absorbent layer, at least one semi-permeablebacking layer and a pressure adhesive layer continuous around theperimeter of the backing layer.

[0114] In another aspect of the invention, the wound dressings can beused to regulate the moisture level of a wound of a human or animal.Many dressings are available that attempt to control the moisture levelof wounds. Moisture retention is a term that refers to the ability of adressing to consistently retain moisture at the wound site byinterfering with the natural loss of moisture vapor due to evaporation.Semi-occulsive and occlusive wound dressings, such as films, foams,hydrogels and hydrocolloids, can be used to keep a wound moist bycatching and retaining moisture vapor that is being lost by the wound.Normal skin has a moisture vapor transfer rate (MVTR), also called atransdermal water loss (TWL), of 43.2 grams/meter²/24 hours. Many filmdressings have MVTRs ranging from 400 to 2000 grams/meter²/24 hours.Superficial wounds such as tape-stripped skin have an initial MVTR of7,874 grams/meter²/24 hours. In general, if a dressing materialtransmits less moisture vapor than the wound loses, then the wound willremain moist. When wound drainage levels are high, simple transmissionof vapor will not dissipate adequate moisture to maintain physiologictissue hydration. If the moisture vapor transmitted by a dressing issignificantly less than the moisture being lost by the wound in vaporand liquid form, then drainage accumulates and remains in contact withthe wound and surrounding skin. To maintain high drainage levels, adressing must also have a liquid absorptive capacity in addition tovapor transmission ability. The process of absorption physically movesdrainage away from the wound's surface and edges and into the dressingmaterial. At the other end of the hydration spectrum, wound tissue thatis already dry may need to be actively re-hydrated using dressingmaterials that donate water to the tissue or by removing the dressingand manually applying fluids to the wound.

[0115] One of the embodiments of the present invention allows for theaddition or removal of fluid from the wound without removing thedressing. This control of fluid can be extremely important in trauma orbattlefield situations where fluids need to be provided quickly.Additionally, the presence of the metal ions, provided by the conductivefibers or foams, aids in control of microbial contamination and thus,non-sterile fluids can be used. The moisture level of the wound can beregulated in comparison to some pre-determined level of moisture thatcan be beneficial. Advantageously, an indicator can be added to thewound dressing to indicate moisture level, electrical potential,metallic ion concentration, or pH.

[0116] To treat wounds, of an animal or human, the appropriate aspect ofthe wound dressing is selected and positioned on the wound, with theconductive layer in contact with the wound. The absorbent layer of thedressing is observed for variation of a moisture level that has beenpredetermined to be advantageous. Moisture, fluids, and medicants can beadded to the wound dressing as needed through the moisture regulationlayer. Moisture in excess of the predetermined level can also be removedthrough the moisture regulation layer. Alternatively, the moistureregulation layer can be removed and replaced with a new moistureregulation layer without disturbing the healing wound. Means to add andremove moisture include, but are not limited to, sponges, suction bulbs,syringes, gauze pads and the like.

[0117] In another aspect of the invention, a secondary dressingcomprising at least one absorbent layer, at least one semi-permeablebacking layer, and a pressure adhesion layer can be affixed to theexternal surface of the wound dressing. The secondary dressing cancomprise liquids and/or medicants for treating the wound. The secondarydressing can be removed and replaced as needed to encourage continuedhealing of the wound.

[0118] In another aspect of the invention, the wound dressing can beplaced internally to treat an organ or internal surgical incision. Thedressing can be in the form of a gauze pad, packing material, fibrousdam, or any means to convey the treatment of the wound.

[0119] The wound dressing, when saturated and overlapping normal skin,may allow for controlled maceration of the surrounding uninjured skin.It is currently believed that the maceration of normal skin should beavoided. Maceration of normal skin is known to cause a breakdown of thecornified epithelium with subsequent loss of the anti-microbial barrierfunction of the skin. The reduction of the anti-microbial barrierfunction of the cornified epithelium is believed to result in anincreased risk of microbial contamination at the wound surface. In aneffort to control and prevent skin maceration, wound dressing designershave constructed wound dressings with special features that reduce theoccurrence of maceration. Without wishing to be bound, the presentinvention has unexpectedly determined that the occurrence of macerationof normal skin surrounding a wound under the wound dressing of thepresent invention has not resulted in increased bioburden and/orcontamination of the wound surface. While not wishing to be bound to anyparticular theory, the present invention has determined that themaceration of normal skin surrounding a wound being treated by thepresent invention has altered the local electrodynamic characteristicsand resulted in an enhancement of the wound healing process.

[0120] It has been observed that regulating the moisture in and aroundthe metal-plated fibers of the wound dressings of the present inventionmay facilitate the release of metallic ions from the surface of themetal because the passive release of metal ions can only take placewithin a liquid medium. Therefore, it is advantageous to keep the wounddressing moist in order to provide the effect of the metal platedfibers. Wounds that generate fluid exudates will usually provide theneeded moisture required to activate the release of metal ions from themetallic surface.

[0121] Methods of Making

[0122] The preferred method of plating a metal on a fiber or foam forthe conductive layer of the present invention is autocatalyticallyplating because it coats the fiber or foam uniformly with a threedimensional coating. This provides the maximum available surface areafor accessible metal ions. In general, the fiber or foam has a nitrogengroup. If the material from which the fiber or foam is made does notprovide a nitrogen group on the surface, such nitrogens can be providedby added a layer of material or a coating that provides a nitrogen groupon the surface. The present invention comprises use of materials thatcan be sensitized for autocatalytic metal plating. Such materials can bemade into fibers, foams, films or other structures that function toprovide the wound healing attributes of the devices described herein.For example, such materials include, but are not limited to, materialshaving nitrogen or silicon dioxide or other equivalently functionalgroups, that are capable of being sensitized. With, for example, thenitrogen group or silicon dioxide on the surface, the material can thenbe sensitized using methods known in the art. Once the material issensitized, autocatalytic metal plating or coating of the material isperformed.

[0123] The principle benefits of autocatalytically metal plating are:(1) uniform circumferential, three dimensional metal plating of thefilament, foam, fiber, yarn or fabric; (2) large ratio of total metalsurface area to geometric surface area; (3) high conductivity and lowresistivity of the plated filaments, fibers, yarns and fabrics; (4)excellent adherence of the metallic coating to the non-conductingpolymeric substrate with reduced risk of the metal coating flaking orfracturing off the non-conducting substrate; (5) excellent flexibility,conformability and elastomeric qualities; and (6) no limitations onfilament, fiber, yarn or fabric design and construction.

[0124] Autocatalytic plating describes the method of depositing metalsor metal alloys on non-conductive substrates by means ofreduction-oxidation chemical reactions. Unlike electroplating,autocatalytic plating does not apply an electrical current from anexternal source to a conductive material or substrate for the purpose ofdepositing metals on the surface of the substrate. If the substrate isnon-conductive, electroplating is not possible. Pure metal elements suchas copper, gold, nickel and silver as well as binary alloys of nickel,cobalt or palladium with phosphorus or boron can be plated ontonon-conductive material or substrate by the autocatalytic platingprocess.

[0125] The autocatalytic plating baths are designed such that when asensitized substrate is introduced into the plating bath, deposition ofthe metal begins in a slow and uniform manner on all surfaces of thesubstrate. Once the process is initiated, the plating solution willcontinue to plate because the deposited metal catalyzes its own plating,thus making the reaction autocatalytic.

[0126] The autocatalytic metal plating process is the plating process ofchoice for filaments, fibers, yarns and fabrics in the electro-staticdischarge, electromagnetic interference and radio frequency interferenceindustries. Autocatalytic metal plating of non-conductive substrates isused because the process is known to be superior to the vacuum vapordeposition process, the sputter coating deposition process, includingmagnetron sputtering, and the ion-beam assisted deposition processbecause it provides greater conductivity and resistivity of the platedsubstrate. Unlike vacuum vapor deposition, the sputter coatingdeposition and the ion-beam deposition processes, filaments, fibers,yarns and fabrics (woven, knitted, and non-woven) that have been metalplated by the autocatalytic process result in three dimensionalcontinuous conductive pathways, while retaining the physical propertiesof the base material. Vacuum vapor deposition and sputter coating areinferior because they plate substrates in two dimensions with subsequentshadows, lack uniformity of the plated metal coatings, and alter theflexibility and conformability of the substrate. Vacuum vapor depositionand sputter coating typically plate substrates in a “line of sight”manner similar to commercial spray painting with compressed air.

[0127] Once the fibers are coated with a metal or metal alloy, they canbe assembled into yarn, cord, thread, fabric, or combinations thereof,to form a layer of woven, knitted or non-woven fabric. The layers areassembled in any configuration predetermined by the intended aspect ofthe wound dressing. Autocatalytic silver plated fibers, filaments, yarnsand fabrics are commercially available from Conductive Specialty FabricsManufacturing LLC, Lakemont, Ga.

[0128] The present invention comprises a method of manufacturing adressing, wherein the dressing comprises at least one conductive layer;at least one absorbent layer; and at least one moisture regulationcomprising a plurality of apertures disposed in the moisture regulationlayer comprising, a) creating apertures in the moisture regulationlayer, b) providing the conductive layer and the absorbent layer, c)assembling the absorbent layer, the moisture regulation layer and theconductive layer each on top of the other to form a contiguous fabric,and d) laminating the fabric of step c. The lamination step is performedby methods known in the art, including but not limited to, pressuresensitive adhesives, heat pressure lamination, flame lamination, hotmelt lamination, point embossing, point bonding, spot bonding, sewing,or a combination thereof. The present invention also comprises a methodof manufacturing a dressing, wherein the dressing comprises at least oneconductive layer, at least one absorbent layer; and at least onemoisture regulation layer positioned adjacent the absorbent layer oradjacent the conductive layer and comprising a plurality of varyingsized apertures disposed in the moisture regulation layer, a) providingthe conductive layer, the moisture regulation layer, and the absorbentlayer, b) assembling the absorbent layer between the moisture regulationlayer and the conductive layer, c) laminating the fabric of step b, andd) creating apertures in the moisture regulation layer. Creatingapertures comprises making the appropriately sized and shaped aperturesin the moisture regulation layer using whatever means will create theaperture. Cutting, piercing, premolding the fabric to include theapertures and similar actions are intended by the term creatingapertures. Lamination is performed by pressure sensitive adhesives, heatpressure lamination, flame lamination, hot melt lamination, pointembossing, point bonding, spot bonding, sewing, or a combinationthereof.

[0129] The assembled layers of the woven, knitted or non-woven fabric ofthe present invention can be laminated by any manufacturing method knownin the art for assembling layers of 100% conductive metallized fibers,layers of varying ratios of conductive metallized fibers tonon-conductive fibers, layers of absorbent material, semi-permeable orimpermeable film or foam, and backing sheets with pressure sensitiveadhesives. Such methods can include, but are not limited to, heatpressure lamination, flame lamination, hot melt lamination or anycombination thereof. Apertures can be cut in the moisture regulationlayer prior to assembly of the layers, or alternatively, after thelayers are laminated, using any manufacturing methods known in the art.The preferable method for placement of the apertures in the moistureregulation layer or the laminate of the moisture regulation layer, skinadhesive and backing sheet is to cut the apertures after the layers arelaminated. Advantageously, a kiss cut method with a rotary cutting edgedye can be used to cut through only the moisture regulation layer orlaminate of the moisture regulation layer, skin adhesive layer andbacking sheet without disturbing the absorbency pad or wound contactlayers. Alternatively, the moisture regulation layer or laminate of themoisture regulation layer, skin adhesive layer and backing sheet can becut prior to lamination of the fabric, or the moisture regulation layercan be cut prior to assembly of the dressing.

[0130] One means for laminating and electrically integrating the layersis by point embossing or point bonding achieved by passing the fabricbetween a pair of niprolls, one roll having a series of spaced pinsextending radially from the roll, and the other roll being flat. As thefabric layers are passed between the niprolls, the pins press into thefabric and force the fibers of one layer into the interstices of thenext layer, thus bonding the two layers by fiber-to-fiber interactionforces. Alternatively, the layers can be laminated by adhesives, spotbonded (by ultrasonic welding or laser welding) or other techniquesknown to those skilled in the art. An alternative technique forlaminating the layers is by sewing them together with conductive thread,preferably autocatalytic silver nylon plated poly or monofilament silvernylon thread. The conductive laminating thread enhances the overallconductivity of the conductive layer 114 and minimizes the resistance.

[0131] The wound dressings of this invention are most suitable whensterile. Preferably the dressings of this invention are provided sealedwithin a microbe-proof package. The dressing may be rendered sterile,for example, by gamma radiation. Surprisingly, it has been determinedthat the silver ion release concentration in aqueous solutions isimproved with gamma radiation.

[0132] With respect to prior art, the application of metallic and ionicsilver in the construction of wound dressings has focused on theanti-microbial aspects of silver and silver ions. The ability of themetallic surface to release particles of metallic silver or silver ionswas related to the anti-microbial aspect of the dressing. The volumeresistivity and conductivity was not addressed. In the presentinvention, resistivity and conductivity contribute to the capabilitiesof the wound dressing.

[0133] The present invention is further illustrated by the followingexamples, which are not to be construed in any way as imposinglimitations upon the scope thereof. On the contrary, it is to be clearlyunderstood that resort may be had to various other embodiments,modifications, and equivalents thereof which, after reading thedescription herein, may suggest themselves to those skilled in the artwithout departing from the spirit of the present invention and/or thescope of the appended claims.

EXAMPLE 1

[0134] A dressing of the present invention was used to treat a 45 yearold male suffering from cutaneous manifestation of “shingles”, Herpeszoster virus unilaterally at the tenth thoracic dermatome measuring 2inches by 3 inches. The patient applied the multilayer wound padillustrated in FIG. 4 after moistening the pad with tap water. Thedressing was held in place with an adhesive layer and backing sheetWithin five minutes, the patient reported 25% reduction in pain andwithin 2 hours nearly 90% reduction in pain. The patient reported thatas the dressing dried out the pain returned, but never returned to thelevel experienced prior to placement of the dressing. When the dressingwas re-moistened with water, the pain level was significantly reducedwithin ten minutes. The dressing was moistened through the moistureregulation layer without removing the dressing from the cutaneous viraloutbreaks. The cutaneous lesions healed within 36 hours afterapplication.

EXAMPLE 2

[0135] A three year old female received 80% total body surface area fullthickness (third degree burns) burns secondary to a flame injury. Shewas taken to surgery shortly after admission and all body surface areaswere debrided of necrotic tissue. Integra® synthetic skin was appliedand covered with the wound dressing illustrated in FIG. 4. The dressingwas changed every two days leaving the synthetic skin in place.Gradually the synthetic skin was surgically excised and meshed splitthickness skin graphs were applied. The wound dressing was applied overthe meshed split thickness skin graphs, and was changed every two daysuntil the wounds healed. The dressing was moistened every 12 hours withsterile water throughout the course of healing.

EXAMPLE 3

[0136] Table 1 illustrates the release of silver ions. A four inch byfour inch square of an autocatalytic electroless silver plated 5.5 ounceper square yard warp knit fabric was incubated in tryptic soy broth at37° C. The concentration of silver ions was measured by inductivelycoupled plasma spectroscopy over a twelve day period. FIG. 4 illustratesthat the concentration of silver ions increased from less than 10micrograms/ml the first hour, to over 60 micrograms/ml by day 5. Table 1Time Dress- 2 3 5 8 12 ing 1 Hr 2 Hr 4 Hr 24 Hr Day Day Day Day Day 4inch 8.5 13.9 19.1 43.1 51.9 58.1 65.4 64.5 64.2 by 4 μg/ml μg/ml μg/mlμg/ml μg/ml μg/ml μg/ml μg/ml μg/ml inch 5.5 oz/yd²

[0137] It is well known that between 3 and 25 micrograms/milliliter ofionic silver are required to kill the most common pathologic woundmicroorganisms. Results indicated that the effective silver ionconcentration was attained in about 1 to about 4 hours.

EXAMPLE 4

[0138]FIG. 5 and Table 2 demonstrate the anti-microbial activity of afour inch by four inch sample of autocatalytically silver plated 5.5ounce per square yard warp knit fabric. The fabric was positioned onmedia that was inoculated with pathogenic organisms Pseudomonasaeuroginosa and Staphylococcus aureus and incubated at 37° C. Growth ofthe organisms were measured by the “ASTM Standard Test Method forDetermining the Anti-microbial Activity of Immobilized Anti-microbialAgents Under Dynamic Contact Conditions” ASTM E 2149-01. The reductionin CFU/ml from 10⁶ CFU/ml of Pseudomonas aeuroginosa ATCC 9027 andStaphylococcus aureus (MRSA) ATCC 33591 was studied. The reduction inorganism counts expressed in colony forming units (CFU) per milliliterwas measured at 0 hours, ½ hour, 1 hour, 1 ½ hour, 2 hours and 4 hours.TABLE 2 Time Bacterial 0.5 1.0 1.5 2.0 4.0 Species 0 Hour Hour Hour HourHour Hour Staphylococcus 1,500,000 210,000 3,400 2,500 120 0 aureusCFU/ml CFU/ml CFU/ml CFU/ml CFU/ml MRSA ATCC 33591 Pseudomonas 2,400,0000 0 0 0 0 aeruginosa CFU/ml CFU/ml CFU/ml CFU/ml CFU/ml CFU/ ATCC 9027ml

EXAMPLE 5

[0139] A study was conducted to determine the efficacy of a wounddressing of the present invention when used with Integra®, an artificialskin used for burn treatment.

[0140] A wound dressing was constructed comprising autocatalytic platedsilver fibers for the conductive layer, and one layer of absorbentmaterial was positioned between the conductive layer and the moistureregulation layer. The moisture regulation layer was constructed of apolyurethane film with 5 mm slit-shaped apertures cut into the layer.

[0141] The Integra® was prepared according to the manufacturer'sdirections to remove the EtOH preservative, and was cut into squares of1.5 inches. Ten squares were used to test Staphylococcus aureus and tensquares were used for Pseudomonas aeruginosa. A seam was created in eachsquare to simulate two pieces of Integra® being joined together to covera wound. Each Integra® piece was centered on an individual standardblood agar plate. Each piece of Integra® was completely covered with a 2inch square piece of wound dressing of the present invention andincubated at 37° C. for 24 hours. At 24 hours, two drops (≈100microliters) of a suspension containing greater than 10⁵, colony formingunits per milliliter of Pseudomonas aeruginosa or Staphylococcus aureuswere added to the center of each dressing, simulating contamination inthe post-operative patient. The dressings were re-moistened andincubated for 48 hours. After 48 hours, the dressings and the Integra®were carefully removed using sterile technique. Cultures were obtainedfrom the area of the plate that was once covered with Integra, beingsure to swab across the area where the seam in the product had been.Fresh agar plates were streaked with these samples and incubated for 24hours.

[0142] The results are noted in the chart below. Staphylococcus aureus(MRSA). Pseudomonas aeruginosa Time +growth −growth +growth −growth 72Hr 6 plates 4 plates 3 plates 7 plates

[0143] The results illustrated that, when used in conjunction withIntegra® artificial skin, the wound dressing of the present inventionwas 70% effective in preventing growth of Pseudomonas aeruginosa and 40%effective in preventing growth of Staphylococcus aureus.

EXAMPLE 6

[0144] A test was conducted to determine the anti-microbial efficacy ofa wound dressing of the present invention in an in vitro setting. Bloodagar plates streaked with broth containing 10⁶ CFU per milliliter ofPseudomonas aeruginosa and Methicillin Resistant Staphylococcus aureus(MRSA) were tested.

[0145] A wound dressing of the present invention was constructedcomprising autocatalytically plated silver fibers for the conductivelayer, and one layer of absorbent material was positioned between theconductive layer and the moisture regulation layer. The moistureregulation layer was constructed of a polyurethane film with 5 mmslit-shaped apertures cut into the layer.

[0146] Ten blood agar plates were streaked with broth containing 106 CFUof Pseudomonas aeruginosa and ten blood agar plates were streaked withbroth containing 106 CFU of Methicillin Resistant Staphylococcus aureus(MRSA). One inch square of the wound dressing of the present inventionwas placed in the center of each of ten blood agar plates. The remainingfive plates were used as controls. The plates were incubated at 37° C.and sterile water added as needed to maintain moist dressings. After 72hours, a culture was obtained from under each dressing and plated onblood agar. These plates were then incubated for 24 hours and evaluatedfor bacterial growth. This process was repeated after six days.

[0147] The results of bacterial growth were counted and recorded in thetable below. Staphylococcus aureus (MRSA). Pseudomonas aeruginosa Time+growth −growth +growth −growth 72 Hr 4 plates 4 plates 4 plates 4plates  6 Days 0 plates 5 plates 0 plates 5 plates

[0148] The conclusion was that the wound dressing was effective inkilling Methicillin Resistant Staphylococcus aureus (MRSA) andPseudomonas aeuroginosa. Prolonged exposure to established bacterialgrowth resulted in progressive death.

[0149] Although the invention has been described in detail for thepurpose of the illustration, it is understood that such detail is solelyfor that purpose, and variations can be made therein by those skilled inthe art without departing from the spirit and scope of the invention,which is defined by the following claims.

What is claimed is:
 1. A wound dressing, comprising, at least oneconductive layer; at least one absorbent layer; and at least onemoisture regulation layer comprising a plurality of apertures disposedin the moisture regulation layer.
 2. The dressing of claim 1, whereinapertures of the moisture regulation layer allow passage of materialsranging in size from no passage of materials to passage of microbial orenvironmental contaminants.
 3. The dressing of claim 1, wherein themoisture regulation layer is attached to the at least one absorbentlayer or the at least one conductive layer.
 4. The dressing of claim 1,wherein the conductive layer comprises at least one fiber that is coatedthree dimensionally with a metal or a metal alloy.
 5. The dressing ofclaim 4, wherein the metal is selected from copper, silver, gold,palladium, nickel, cobalt or a combination thereof.
 6. The dressing ofclaim 4, wherein the metal is selected from an alloy of nickel andboron, cobalt and boron, palladium and boron, nickel and phosphorus,cobalt and phosphorus, palladium and phosphorus, or a combinationthereof.
 7. The dressing of claim 1 wherein the conductive layercomprises a polymeric foam coated three dimensionally with metal or ametal alloy.
 8. The dressing of claim 1, wherein the conductive layercomprises at least one fiber or foam having grooves or channels alongthe longitudinal axis of the fiber or foam for capillary movement ofwater, to store or trap substances, and to provide large active surfaceareas for a given denier per fiber or foam.
 9. The dressing of claim 1,wherein the at least one conductive layer comprises at least oneconductive fiber comprising a three dimensional coating of a metal, andat least one non-conductive fiber, wherein the conductive fiber andnonconductive fiber are uniformly distributed throughout the layer. 10.The dressing of claim 9, where in the nonconductive fiber is composed ofnatural polymers, synthetic polymers, alginates, chitosan, rayon,cotton, or polymeric substrates.
 11. The dressing of claim 9, whereinthe at least one absorbent layer is a plurality of layers wherein theratio of conductive fibers to non-conductive fibers is constant in agiven layer or varies from layer to layer.
 12. The dressing of claim 11,wherein the ratio of conductive fibers to non-conductive fibersincreases as the absorbent layer is positioned in closer proximity tothe wound.
 13. The dressing of claim 1, wherein a magnetic field isprovided to the wound surface by the conductive layer.
 14. The dressingof claim 1, further comprising an adhesive layer.
 15. The dressing ofclaim 1, wherein the at least one conductive layer comprises a fiber orfoam three dimensionally coated with a metal.
 16. The dressing of claim1, wherein the at least one absorbent layer comprises conductive fiberscomprising a three dimensional coating of a metal, and non-conductivefibers, wherein the conductive fibers and nonconductive fibers areuniformly distributed throughout the layer.
 17. The dressing of claim16, where in the fibers are composed of natural polymers, syntheticpolymers, alginates, chitosan, rayon, cotton, or polymeric substrates.18. The dressing of claim 16, wherein the ratio of conductive fiber tonon-conductive fiber is between about 1:100 to 1:0.
 19. The dressing ofclaim 16, wherein the ratio of conductive fiber to non-conductive fiberis between about 1:50 to 1:0.
 20. The dressing of claim 16, wherein theratio of conductive fiber to non-conductive fiber is between about 1:25to 1:0.
 21. The dressing of claim 16 further comprising at least onemoisture regulation layer positioned adjacent to the at least oneabsorbent layer.
 22. The dressing of claim 1, wherein the absorbentlayer is polymeric sheets, films, or foams.
 23. The dressing of claim22, wherein the moisture regulation layer has apertures.
 24. Thedressing of claim 22, wherein the moisture regulation layer does nothave apertures.
 25. The dressing of claim 1, wherein there are multiplelayers of conductive and absorbent layers.
 26. The dressing of claim 25,wherein the at least one absorbent layer comprises a plurality oflayers, each layer increasing in thickness as the proximity from thewound increases.
 27. The dressing of claim 25, wherein the conductivelayers and absorbent layers alternate.
 28. The dressing of claim 1wherein the apertures comprise a geometric shape having curved lines,straight lines, or a combination thereof.
 29. The dressing of claim 1made into a shape selected from a pad, a tampon, a tubularconfiguration, an island dressing, a strip dressing, or any combinationthereof.
 30. A secondary dressing for applying to a wound dressingcomprising at least one absorbent layer, at least one semi-permeablebacking layer and a pressure adhesive layer continuous around theperimeter of the backing layer.
 31. A method of treating a wound in ahuman or an animal comprising, a) applying a dressing to a wound on ahuman or animal wherein the dressing comprises at least one conductivelayer; at least one absorbent layer; and at least one moistureregulation layer comprising a plurality of apertures disposed in themoisture regulation layer; b) monitoring the absorbent layer of thedressing to determine a variation from a predetermined fluid level; andc) adding or removing fluid through the moisture regulation layer tomaintain the predetermined fluid level.
 32. The method of claim 21further comprising: affixing a secondary dressing to the externalsurface of the dressing applied in step a) to the wound, wherein thesecondary dressing comprises at least one absorbent layer, at least onesemi-permeable backing layer and a pressure adhesive layer continuousaround the perimeter of the backing layer.
 33. A method of manufacturinga dressing, wherein the dressing comprises at least one conductivelayer; at least one absorbent layer; and at least one moistureregulation comprising a plurality of apertures disposed in the moistureregulation layer comprising a) creating apertures in the moistureregulation layer, b) providing the conductive layer and the absorbentlayer, c) assembling the absorbent layer, the moisture regulation layerand the conductive layer each on top of the other to form a contiguousfabric, and d) laminating the fabric of step c.
 34. The method of claim24 wherein the lamination step is performed by pressure sensitiveadhesives, heat pressure lamination, flame lamination, hot meltlamination, point embossing, point bonding, spot bonding, sewing, or acombination thereof.
 35. A method of manufacturing a dressing, whereinthe dressing comprises at least one conductive layer, at least oneabsorbent layer; and at least one moisture regulation layer positionedadjacent the absorbent layer or adjacent the conductive layer andcomprising a plurality of varying sized apertures disposed in themoisture regulation layer a) providing the conductive layer, themoisture regulation layer, and the absorbent layer, b) assembling theabsorbent layer between the moisture regulation layer and the conductivelayer, c) laminating the fabric of step b, and d) creating apertures inthe moisture regulation layer.
 36. The method of claim 35 wherein thelamination step is performed by pressure sensitive adhesives, heatpressure lamination, flame lamination, hot melt lamination, pointembossing, point bonding, spot bonding, sewing, or a combinationthereof.